1. Field of the Invention
This invention relates to a transfer device that transfers a toner image formed on an image bearing member to a sheet, and an image forming apparatus including the transfer device.
2. Description of Related Art
In one image forming apparatus, a toner image formed on a photoreceptor drum is transferred to a sheet. In another image forming apparatus, a toner image formed on a photoreceptor drum is transferred primarily to an intermediate transfer belt and the toner image is transferred secondarily to a sheet from the intermediate transfer belt. The sheet including the transferred toner image is carried to a fixing device via a transfer position for the toner image. At this time, it is very likely that the sheet will be drawn toward an image bearing member such as a photoreceptor or an intermediate transfer belt, etc. by the action of electrostatic force generated in the sheet. Hence, a technique of stripping the sheet including the transferred toner image from the image bearing member has conventionally been suggested.
According to one exemplary technique, an electric field is formed on the opposite side of an image bearing member across a sheet to strip the sheet electrically. This technique is implemented by using a sawtooth electrode employed in a corona charging device described in Japanese published unexamined patent application No. 10-90974 (1998), for example.
The sawtooth electrode has a sharply pointed tip at each saw tooth. This causes risk of deformation of the sawtooth electrode due to touch with the sawtooth electrode by a sheet during carrying of the sheet or touch with the sawtooth electrode by a user or a repairman during maintenance. Deformation of the sawtooth electrode causes risk of interfering with formation of an electric field intended for stripping of a sheet. If a sufficient electric field is not formed, a sheet wraps around an image bearing member before being carried to a fixing device and this becomes a cause for a paper jam.